Primary torsion dystonias (PTDs) are a group of movement disorders characterized by twisting muscle contractures, where dystonia is the only clinical sign (except for tremor) and there is no evidence of neuronal degeneration or an acquired cause. Seven genes have been mapped for primary dystonia including DYT1, 2, 4, 6, 7, 13 and 17, however until recently, the genetic basis for only one of these, DYT1, responsible for most cases of early onset generalized dystonia, has been identified and is caused by a heterozygous three basepair in-frame deletion in the TOR1A gene. This mutation accounts for about 90% of early onset PTD cases in the Ashkenazi Jewish population due to a founder effect but in the non-Jewish population it accounts for less than 50%. We have recently identified a new early onset PTD gene, THAP1, mutations in which cause DYT6 dystonia. In this application, we will generate overexpressing transgenic mice harboring the human THAP1 wt or mutant protein and will generate a Thap1 neuronal specific conditional knock-out mouse. We will study these mice to determine the normal function of the THAP1 gene product and whether the disease is caused by a gain or loss of function mechanism. All mice generated in this project will be evaluated for neurologic and motoric phenotypes and undergo neurochemical and neuropathological analyses. Development of mouse models specific for DYT6 dystonia will allow for the determination of common mechanisms among early onset PTDs and provide the foundation for devising novel treatments for these poorly understood and disabling diseases. PUBLIC HEALTH RELEVANCE: The genetic basis of most Primary torsin dystonias (PTD) remains unknown and the pathophysiological mechanisms are poorly understood. Treatment is incomplete and empiric. With the discovery of a new PTD gene we can now generate mouse models specific to this disorder. Development of these models will provide a unique tool to clarify the underlying mechanisms of dystonia and provide the foundation for devising novel treatments for these poorly understood and disabling diseases.